Strength and toughness of semicrystalline polymer fibers: Influence of molecular chain entanglement

Abstract

The mechanical properties of oriented semicrystalline polymers fibers are mainly determined by the semicrystalline morphology in which lamellar crystals and disordered amorphous layers are in staggered arrangement. As a stress transmission channel, amorphous entanglement network can affect the strength and toughness of fiber together with crystalline phase. In this study, the relationship between mechanical properties and amorphous entanglement of oriented poly (l-lactic acid) fibers was clarified by studying the cyclic loading characteristics. Based on the Haward-Thakray model of semi-crystalline polymers, the energy contributions of the crystalline phase and the amorphous phase are separated. During the deformation of oriented fiber, the crystal will be broken under the action of tight entanglement network, and the entanglement network can transfer stress well without failure under the action of straight chain. Therefore, although the crystalline phase and the amorphous phase jointly bear the strength, the toughness and fracture behavior mainly affected by the entangled network of the amorphous phase.